Conversion of metals into metal oxides and hydroxides



Feb. 23, 1954 MUNN 2,670,273

CONVERSION OF METALS INTO METAL OXIDES AND HYDROXIDES Filed April 10, 1947 INVENTOR John 15' Mann ATTORNEYS Patented Feb. 23, 1954 UNITED GFFlC-E' CONVERSION OF METALSE'NIN'IQVMETALJ oxmss snn HYnRoxmEs which, of itself, is a desiravble commercial Ina-s terial. Alternatively, the, copper sheathingI or copper-cladsteel mayiloe c'olrivertedinto=copher oxide while the ferrous base isleftuntouched, so thatthe copper oxide maylbeusedzas such, or it may be smelted into copper and, the ferrous; base canbe usecl as ferrous ne lting.scrap. Thus the invention isapplicaljle either-tomaking:metal compoun s from a; metal or for; separatingphysically eombinedimetais by converting oneot themvinto a compound. V I

This invention differs from all knownmethocls of 7 converting. metals to metallic compounds by leaching or like reactions, in" that metal isv continuclisly. reacted in, the presence oi?- an ,electro;--

ly't'e and Icontlhuously precipitated as a compound;

atthe same time from the; sameghody f eleotro lyt without exhaustion oflthe-electrolyte-.1, This so far as rcanawsaam, is anew phenomenon In all usual operations 0t leaching; the nstal is 7 reacteol 1 with the electrolyte until the electrolyte:

is spent, orwill no longer react ,wl tnmetal, The? electrolyte is: then .proc's'sed'lto:reeover mamas; compound" dissolved or, cohtained thereinr; and;

the electrolyte so use 'is" eiih'au'st dl Itmust be constantly replenishii; With :my process, except for certain inevitableihandling losses the electrolyte is usame ovfj and, over. without liroces'sing in any: way.

invention, haslibeen successfully. mploy s,

withseverm metals; and; the compounds; and ac'fibfdin g to following conditic'in's are required? (1) The electrolyte-used? must-he -one whi corrosive-toathe metalit'o:b'eeOnVei t co sjoaseveral,

pounds. That is, it will be capable er ata-king the metal. from-which the compounds: are to be d?- (2') The process mustbe'carrie'd out in a closed; environment Where alternate exposure to j the atmosphere aridfliduixl inmeenvirenmenrmayhe efieete'dr invention: the;

I (3) There mustbe' presentein the-closedien-ovironment or; reactor a: gas which enters into combination with the metal.

Essentially my inventioncontemplates the tumbling: of: the; metal in. a; corrosive liquid and 3111 atmosphere; of. axgas which:,isoonsumed'in: the" reaction so': than. the metal vis a1ternate1y im= m-ersed in the: liquid? and: exposed: to the"; gas: Temperature; conditions and; the; concentration;

- oil the electrolyte may:also'in some: cases. control a the character of the; product;

My invention may be more fully: understood: by reference to the accompanying"; drawings; in which' the figure -is:a view partly; in section and;

I partly: elevation and scher'naticiini ch'aracten of anzapparatusr embodying: and capable; of: ef+- footing: my invention;

In thedrawing; {designates an: enclosed ves-zsel or reactor, .v preferably rectangular in shape; having: a: trunnion 3 at: one end on? which is a" pulley 4 shy *meanstof which ithesvessel may be T0; tated.. The vessel has: a cover member 5 re'- movably sealed thereto so'v as to be liquid and ga's tighfl but: which ali'ortls' access to: the' in ter'ior of the'zv'essel for. charging 'ancl'ciischarging the contentsa-of the-vessel: The vessel is also show'n as iliaving-a drainxvalve "5':

At the other: enoll of the vessel is a hollow: trunnion fi ihaving a gland: 9 'into which a' gas supply-1 pipe illeisentere'dz Thispipe H3 is'provide'di%w-ith:a:out=ofi:valve H; a drain valv'e' l2; apressu're regulating valve" l3',ranc1'an eitension it. With this arrangement the vesselinay-beselectivelyfconnected through apressure reg'ulator and manifold" to: one" or another gasstorage-= vessel: I57 soithat" when one vessel is exhausted,- another may: lie us'e'wwhile the --'f\-rst is reQI-a'ced; or; when necessary; two difi erent asesmay be supplied simultaneously or. successively to the reactor.

them-swings, spray nozzles Ell 'ar'e sliown foi=-dirc-ti-ng ets-or coling'fluid"againsttheout side of thedrum: The" may he 1 provided with heat dissipating fins, shown, toac celerate the rate of beat-transfer. Water, or even air currents may,v be directed through the ozz es: othe'rgnozzlestrma alsobepmvidm fdrdif'ectinga heau'ngfium" o en as steam against. the reactor: It will e apparntthatvafiousv other eirineiaturereeulatifigonmodir mgmam.

lid is sealed shut. The reactor is then set into rotation, and gas is admitted to build up and maintain a desired pressure therein. After a period of time, depending upon the metal, the amount of metal and the product to be produced, the reactor is stopped and opened. The metallic compound is present in the bottom of the reactor as a sludge of very small particles. Usually the valve 7 is opened and the contents of the reactor are run into a thickener or filter to separate out the metallic compound which is subsequently washed and dried, while the electrolyte from which the compound is separated or filtered is kept for reuse in the reactor. It will be found that during the reaction the metal compound is continuously formed and precipitated without exhaustion of the electrolyte, and that no matter how long the electrolyteis used, it will remain active.

With the reactor about one foot in diameter and about six inches long revolving at '72 R. P. M., the following are typical examples of my method.

Example 1 Black copper oxide was prepared by making a solution containing 160 grams of ammonium carbonate-carbamate (ammonium carbonate, commercial grade) and 1000 c. c. of ammonium hydroxide containing 28% NHs and 2000 c. c. of water. These proportions are not critical, however. It will be noted that the solution is corrosive to copper.

This solution filled the reactor to about onethird of its capacity. Commercial copper scrap was then put into the reactor until it was about two-thirds full. The amount of copper is not critical. The cover was then sealed on and oxygen from one of the tanks l5 was admitted, the regulating valve being set to maintain a pressure of 7 p. s. i. in the reactor. Rotation of the reactor was continued for about an hour, and the sludge and electrolyte were then drawn off. The sludge was separated by filtration, the electrolyte recharged into the reactor with additional copper, and enough fresh solution to offset the amount that remained in the sludge was added and the operation repeated. The electrolyte lost none of its effectiveness.

While the operation could have continued until all of the metallic copper had been converted, it is more efficient to replenish the copper from time to time and so keep a good mass of metal in the reactor.

The sludge was black copper oxide, 99+% of which was 1 micron or under in its greatest dimension. The temperature during reaction reached between 165 F. and 175 F., the oxidation of the metal being an exothermic reaction.

Example 2 ,The same procedure was followed with the metals cobalt, zinc, cadmium, nickel and silver, with the production in each case of the corresponding metal oxide.

Example 3 The ammonia concentration of the solution of Example 1 was decreased about 50%, the same amount of copper scrap was charged into the reactor, the oxygen pressure was about the same, small amounts of water were intermittently added, and the reactor was cooled to keep the contents below 165 F. Copper hydroxide was precipitated as a sludge and the electrolyte reused after the hydroxide was separated. Water was added because the formation of the hydroxide tended to remove water and increase the concentration of the ammonia solution. The electrolyte was not depleted by use.

Example 4 Using the solution of Example 1 and a like amount of copper, CO2 and oxygen were both introduced in about equal amounts into the reactor. The gas pressure was around 7 p. s. i. and the temperature was of the order of 165 F. Copper carbonate was precipitated.

Example 5 A solution was prepared with 300 grams of commercial ammonium chloride and 2700 c. c. of water. This was put into the reactor with enough iron scrap to fill the reactor about twothirds full. Oxygen was supplied during reaction at about 7 p. s. i. pressure. Very finely divided red iron oxide was produced. The electrolyte was reused for the treatment of other iron. The temperature reached was approximately 165 F., no control being used. Magnetic black iron oxide may be produced with slight variation of this procedure, which consisted in cutting of the oxygen after red oxide had been produced, whereupon F6203 with additional unreacted iron in the reactor iron formed F6304. Instead of using a solution of ammonium chloride, a corrosive liquid was prepared using sodium chloride.

Example 6 A solution was prepared using 300 grams of .commercial ammonium chloride and 2700 c. c.

of water. scrap. Instead of oxygen, chlorine was introduced into the reactor, and maintained at a pressure about or slightly above 5 p. s. i. Iron chloride in finely divided form was precipitated. The electrolyte was successfully reused.

The same procedure may be followed using sodium chloride as the corrosive agent, or by using HCl or H2804 solution, it being desirable where an acid is used as the corrosive agent, to keep the reactor open during the initial: reaction while hydrogen is being generated.

In the above example, fluorine may be used in place of chlorine, to produce fluorides. Other gases are S02 and S03. The gas in each case must be an active one, that is, one which may form salt or compounds of the metal to be con verted, and the inert gases, such as helium, argon, neon, etc. Gases such as HCl or HzS are not used, because their reaction with metal will occur directly and hydrogen is liberated. The gas therefore is one which may be combined with metal, but which in entering into the combination does not itself decompose.

Example 7 Into a larger reactor, for use in separating copper or gilders metal from ferrous sheet metal on which it is clad, there was charged 2240 lbs. of scrap containing steel, carrying on its surface 20% (average) gilders metal. A solution was then introduced, made with:

370 lbs. of ammonium hydroxide 26 B. 66 lbs. of ammonium carbonate (commercial) 825 lbs. water During rotation of the reactor over a period of two hours, 1600 cubic feet of oxygen were consumed, pressure being maintained at about 5 p. s. i. above atmospheric. After two hours, the oxygen was shut off and the reactor rotated for It was putin the reactor with iron fixed in the solution as such during the process, and thereafter recovering precipitate.

3. The method of forming a copper compound of the group consisting of the oxide and hydroxide from ferrous metal having copper physically associated therewith for the separation and recovery of copper and the refinement oi the ferrous metal, which comprises tumbling the metal pieces in an environment closed against the escape of gases and vapors during the tumbling process containing part liquid and part gas so that in the tumbling process the metal is alternately immersed in the liquid and then exposed to the gas, the gas being commercial oxygen and the liquid being an aqueous solution of an ammonium compound, and supplying additional oxygen to the environment as the oxygen is consumed continuously forming in said environment during the tumbling operation the cuprous compound of the group consisting of the oxide and hydroxide as a precipitate, the strength of the ammonia solution remaining substantially constant and unaltered throughout the process, and subsequently separating out said precipitate and reusing the said ammonia solution so separated in a succeeding similar operation.

4. The method of converting copper to its respective oxides which comprises introducing pieces of the metal to be converted into an environment closed against the escape of gases, introducing a starting aqueous solution of ammonia and commercial ammonium carbonate into said environment to partially fill it, mechanically tumbling the metal and solution about within the environment, and introducing commercial oxygen into the environment during such tumbling continuously precipitating the metal oxide which is produced, the ammonia in the ammonia solution remaining substantially fixed as such in the solution throughout the process and being retained in the solution without substantial depletion by the reaction.

5. The method of converting metals of the group consisting of copper, nickel, cobalt, zinc, iron, cadmium and silver to their respective compounds of the group consisting of the oxide and hydroxide which comprises introducing a charge of the metal pieces to be processed into an environment closed against the escape of gases and vapors, tumbling it in such environment into and out of an aqueous solution containing metalammonia compounds of the metal being treated, simultaneously introducing commercial grade oxygen into the closed environment during such tumbling, continuously forming and precipitat ing in the environment a compound of the metal,

retained in the solution without substantial depletion by the reaction, separating the precipitate from the solution after substantial depletion oi! the metal to recover the precipitate and re-using the solution less only the precipitate in processing other like metal to make more of said compound.

6. The method of stripping copper from cop-.

per clad steel by oxidation of the copper which comprises introducing pieces of the clad metal into an environment closed against the escape of gas and vapors, said environment containing a body of an aqueous solution of a copper-am-v monium compound and containing an atmosphere of commercial grade oxygen, tumbling the charge of metal pieces about in said environment to alternately expose them to the oxygen and immerse them in the solution and effect also mechanical motion of the pieces against one another, whereby the copper on the metal pieces is reacted and stripped, supplying additional commercial grade oxygen to the environment as it is consumed, precipitating in the environment during such tumbling the compound so formed 1 which is a compound of the group consisting of copper oxide and copper hydroxide, the ammonia in the ammonia solution remaining substantially fixed as such in the solution throughout the process and being retained in the solution without substantial depletion by the reaction, terminating the tumbling when the copper has been so stripped and removed therefrom, subsequently separating the compound from the solution to recover such compound and re-using the solution to process more such metal.

JOHN E. MUNN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 143,862 Tuttle et a1. Mar. 24, 1874 298,149 Wright May 6, 1884 682,232 Beck Sept. 10, 1901 884,298 Schaefer Apr. 7, 1908 1,050,678 Moreno Jan. 14, 1913 1,487,145 Caron Mar. 18, 1924- 1,937,524 Marsh Dec. 5, 1933 1,949,927 Carson Mar. 6, 1934 1,963,105 Swift June 19, 1935 1,995,555 Weidma-nn Mar. 26, 1935 2,045,807 Smyly June 30, 1936 2,045,808 Smyly 1 June 30, 1936 2,104,754 Marsh Jan. 11, 1938 2,111,727 Plews Mar. 22, 1938 2,153,300 Dahlen et a1. Apr. 4, 1939 2,339,793 Moeklebust et a1. Jan. 25, 1944 2,339,898 Ravnestad et a1. Jan. 25, 1944 OTHER REFERENCES Prescott and Johnson, Qualitative Chemical Analysis, 5th edition, pages 104, 105, 153, paragraph 8 (1901), D. Van Nostrand '00., N. Y. C. 

1. THE METHOD OF MAKING A METAL COMPOUND OF THE GROUP CONSISTING OF AN OXIDE AND HYDROXIDE FROM PIECES OF THE RAW METAL WHICH COMPRISES TUMBLING THE METAL PIECES IN AN ENVIRONMENT CLOSED AGAINST THE ESCAPE OF GAS AND VAPORS DURING THE TUMBLING PROCESS CONTAINING PART LIQUID AND PART GAS SO THAT IN THE TUMBLING PROCESS THE METAL IS ALTERNATELY IMMERSED IN THE LIQUID AND THEN EXPOSED TO THE GAS, THE GAS BEING COMMERCIAL OXYGEN AND THE LIQUID BEING AN AMMONIACAL SOLUTION WHICH CORRODES THE METAL, THE METAL BEING A METAL OF THE GROUP CONSISTING OF COPPER, NICKEL, COBALT, ZINC, IRON, CADMIUM AND SILVER SUPPLYING ADDITIONAL OXYGEN TO THE ENVIRONMENT AS THE OXYGEN IS CONSUMED THEREFROM AND CONTINUOUSLY DURING SUCH OPERATION USING THE SAME AMMONIACAL SOLUTION AND PRODUCING DURING SUCH OPERATION A METALLIC COMPOUND OF SAID GROUP CONSISTING OF THE OXIDE AND HYDROXIDE FROM THE METAL SO TREATED, THE AMMONIA IN THE AMMONIACAL SOLUTION REMAINING SUBSTANTIALLY FIXED AS SUCH IN THE SOLUTION THROUGHOUT THE PROCESS AND RECOVERING SUCH METALLIC COMPOUND SO FORMED. 